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Why Residential Concrete Driveways Sink And How To Get Them Back Into Place

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Concrete is heavy and bulky. Sometimes its sheer weight will cause a concrete driveway to sink down into the substrate located below it. However, most of the time when concrete sinks there are other factors at play.

Once each of these factors has been properly rectified, then a concrete contractor can lift the driveway slab back into place and ensure it won't sink again.

To better understand why your concrete driveway has sunken and how to get it back into place, here's more information:

The Factors Affecting Concrete Sinking

Unless you live in an area where an earthquake has occurred and damaged the driveway, it has most likely sunken into the ground because it developed a problem with its substrate layer.

The slab's substrate layer is comprised of soil, gravel, and possibly sand. When the concrete was first poured, the substrate would have been graded out flat and then compacted down with a machine until it was very hard.

However, as moisture intrudes under the slab and the soils on your property shift from stormwater, the substrate layer can be damaged. Once the substrate layer has become damaged or loses its integrity, then the slab loses its structural support layer and will either sink into the substrate or form cracks in places where you don't want them.

The Three Things that Damage Driveway Substrate Layers

There are three things that will damage a driveway's substrate layer. They include each of the following: 

  • the substrate layer was not properly compacted
  • too much water has run under the slab and eroded away areas of the substrate
  • the substrate layer has suffered excessive expansion and contraction from weather

If the substrate wasn't properly compacted, then water will run under the driveway and slowly erode away the material below it.

Sometimes, even though the substrate was compacted, it has been exposed to runoff from a roof or landscaping and that has caused it to erode.

As the driveway sits in the weather, the substrate expands and contracts from heat and moisture content. Over time, this can cause gaps in the substrate and lead to sinking problems.

How a Concrete Driveway is Lifted and Restored

Once the cause of your driveway's sinking problem has been addressed, then a licensed concrete contractor will lift the slab up with machinery, repair any damage to the substrate, recompact it, and then place the driveway slab back into place. For more ideas check out other concrete lifting companies.